Secure session management
import 'package:shelf/shelf.dart' as shelf;
class Session {
String id;
DateTime expirationTime;
Session(this.id, this.expirationTime);
}
final sessionMap = {};
shelf.Response handleRequest(shelf.Request request) {
final sessionId = request.headers['sessionId'];
final session = sessionMap[sessionId];
if (session != null && DateTime.now().isBefore(session.expirationTime)) {
// Handle authenticated request
return shelf.Response.ok('Authenticated request');
} else {
// Handle unauthenticated request
return shelf.Response.forbidden('Unauthenticated request');
}
}
void main() {
var handler = const shelf.Pipeline().addMiddleware(shelf.logRequests()).addHandler(handleRequest);
shelf.serve(handler, 'localhost', 8080);
}
The above code is a simple Dart server using the Shelf framework. It uses a basic session management mechanism where sessions are stored in a map and retrieved using a session ID from the request headers.
The vulnerability lies in the session validation within the
handleRequest function. The function checks if the session exists and if it hasn't expired yet. If both conditions are met, it handles the request as an authenticated request.
However, the
expirationTime of a session is stored in the session object itself, which is stored in a map on the server. This means that if an attacker can somehow gain access to the server's memory or the session map, they can modify the
expirationTime of an expired session to a future time, thus making the session valid again.
This is an insecure session management vulnerability because it allows an attacker to prolong a session indefinitely by simply modifying the session's expiration time.
import 'package:shelf/shelf.dart' as shelf;
class Session {
final String id;
final DateTime expirationTime;
Session(this.id, this.expirationTime);
}
final sessionMap = {};
shelf.Response handleRequest(shelf.Request request) {
final sessionId = request.headers['sessionId'];
final session = sessionMap[sessionId];
if (session != null && DateTime.now().isBefore(session.expirationTime)) {
// Handle authenticated request
return shelf.Response.ok('Authenticated request');
} else {
// Handle unauthenticated request
// Remove the expired session from the sessionMap
sessionMap.remove(sessionId);
return shelf.Response.forbidden('Unauthenticated request');
}
}
void main() {
var handler = const shelf.Pipeline().addMiddleware(shelf.logRequests()).addHandler(handleRequest);
shelf.serve(handler, 'localhost', 8080);
}
The updated code includes a mechanism to invalidate the session token once it has expired. This is done by removing the expired session from the
sessionMap in the
handleRequest function. This ensures that once a session has expired, it cannot be reactivated by modifying the expiration time.
The
Session class has also been updated to make the
id and
expirationTime fields final. This means that once a
Session object has been created, its
id and
expirationTime cannot be changed. This helps to ensure that the session expiration time is managed server-side and cannot be modified by the client.
These changes help to mitigate the risk of session token manipulation by ensuring that expired session tokens cannot be reactivated and that the session expiration time cannot be modified after the session has been created.
For further security, consider using a secure session management library that handles these issues automatically, regularly rotating session tokens to limit the potential damage if a token is compromised, and implementing additional security measures such as re-authentication for sensitive operations.